[Asterisk-Users] Re: Asterisk in production as a fax server, anyone?

[Steve Underwood]

Don Pobanz wrote:

> Adolfo R. Brandes wrote:
>
>> Lee Howard wrote:
>>
>>> However, based on the comments you give I'd suspect that you're 
>>> having what people seem to be calling "frame slipping".  There seem 
>>> to be some motherboards that react poorly with Zap cards (or their 
>>> respective drivers) and cause that.  Your zttest results should be 
>>> revealing here.
>>
>
> Frame slips are NOT motherboard related!
>
> A Frame slip is due to clocks at opposite ends of a circuit such as a 
> T1 running at different speeds. Either a buffer overflows and one 
> frame is thrown away or there is no data when a frame is needed so the 
> previous frame is repeated.
>
> The solution is to have one end of the circuit supply the clock and 
> the other end derive the clock from the incoming signal.
>
True frame slips are not motherboard related. However, many people loose 
samples (usually chunks of 8 or 160) due to motherboard (or possibly 
BIOS) issues. Some motherboards seem far more prone than others to 
loosing interrupts at the high rate these boards work. That might be to 
do with the PCI latency settings, or PCI controller effeciency or a 
bunch of other variables. However, the bottom line is people do loose 
samples due to motherboard issues, and "frame slips", not entirely 
unreasonably, tends to get used as a catch all term for these things.

Steve